In the semiconductor processing industry, a photoresist is applied to a semiconductor wafer by means of a spin coating machine. The wafer is placed on a flat vacuum chuck and spun slowly while the photoresist is applied through a nozzle near the center of the wafer. When the wafer is spun at high speed, centrifugal force causes the photoresist to flow towards the circumference of the wafer, thereby covering the surface of the wafer with a smooth, even coat of photoresist. Excess photoresist flows off the edge of the wafer, and is collected and disposed of.